Science: Pluto's Day

Astronomers are cosily familiar with stars quadrillions of miles from
the earth, and with galaxies much more distant. But Pluto, a member of
the sun's own planetary family, and only 3½ billion miles away, has
little personality for them. The outermost member of the solar system,
it shines only feebly by reflected sunlight. Even in the biggest
telescopes it looks like a faint star; only its motion among the real
stars and a slight fuzziness prove it to be a planet. Astronomers are
not sure how big it is (probably midway between Mercury and...